OBJ export: Smoothing group issue #68807

New Issue

cameron casey · 2019-08-18T22:42:49+02:00

cameron casey commented

2019-08-18 22:42:49 +02:00

System Information
Operating system: Win 10
Graphics card: GTX 1070 ti

Blender Version
Broken: (example: 2.80, edbf15d3c044, master, 2018-11-28, as found on the splash screen) 2.80
Worked: (optional) it works fine in 2.79

Short description of error
If you export a shaded object as an obj with smoothing groups checked off in the settings it makes every edge a sharp on that object. but you don't know until you reimport it. Even if you try to fix the object it still seems to have shading issues. This doesn't happen in 2.79 so I assume its a bug.
Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).
Subdivide a cube. make your cube shaded. export as obj file. check smoothing groups on as you export it. Import the obj back in to blender and look at it in edit mode.

**System Information** Operating system: Win 10 Graphics card: GTX 1070 ti **Blender Version** Broken: (example: 2.80, edbf15d3c044, master, 2018-11-28, as found on the splash screen) 2.80 Worked: (optional) it works fine in 2.79 **Short description of error** If you export a shaded object as an obj with smoothing groups checked off in the settings it makes every edge a sharp on that object. but you don't know until you reimport it. Even if you try to fix the object it still seems to have shading issues. This doesn't happen in 2.79 so I assume its a bug. **Exact steps for others to reproduce the error** Based on the default startup or an attached .blend file (as simple as possible). Subdivide a cube. make your cube shaded. export as obj file. check smoothing groups on as you export it. Import the obj back in to blender and look at it in edit mode.

cameron casey commented

2019-08-18 22:42:49 +02:00

Added subscriber: @cameroncasey3d

Philipp Oeser changed title from ~~Smoothing group issue~~ to OBJ export: Smoothing group issue

2019-08-19 12:24:40 +02:00

Philipp Oeser commented

2019-08-19 13:37:06 +02:00

Added subscribers: @mont29, @lichtwerk

Philipp Oeser commented

2019-08-19 13:37:06 +02:00

Hm, not sure I understand correctly:

Here is a file with half flat, half smooth shaded faces:

#68807.blend

in 2.80, when object exports with smoothing groups OFF, reimport (with smoothing groups ON) will result in an edgeloop in the middle being marked sharp
in 2.80, when object exports with smoothing groups OFF, reimport (with smoothing groups OFF) will result in all flat shaded faces being marked sharp

this seems to match 2.79 behavior exactly?

@cameroncasey3d : could you check that example and state if this is unexpected behavior for you? Or provide a better example?

@mont29: if I try to export above file from master with Smooth Groups option ON I am getting following assert:
BLI_assert failed: /blender/source/blender/blenkernel/intern/mesh_mapping.c:738, poly_edge_loop_islands_calc(), at '(((poly_groups[*p]) == (0)) || ((poly_groups[*p]) == (poly_group_id)))'

Hm, not sure I understand correctly: Here is a file with half flat, half smooth shaded faces: [#68807.blend](https://archive.blender.org/developer/F7672935/T68807.blend) - in 2.80, when object exports with smoothing groups OFF, reimport (with smoothing groups ON) will result in an edgeloop in the middle being marked sharp - in 2.80, when object exports with smoothing groups OFF, reimport (with smoothing groups OFF) will result in all flat shaded faces being marked sharp this seems to match 2.79 behavior exactly? @cameroncasey3d : could you check that example and state if this is unexpected behavior for you? Or provide a better example? @mont29: if I try to export above file from master with `Smooth Groups` option `ON` I am getting following assert: `BLI_assert failed: /blender/source/blender/blenkernel/intern/mesh_mapping.c:738, poly_edge_loop_islands_calc(), at '(((poly_groups[*p]) == (0)) || ((poly_groups[*p]) == (poly_group_id)))'`

cameron casey commented

2019-08-19 19:01:45 +02:00

@lichtwerk https://i.imgur.com/MSg1eS1.gifv I made a gif to show you the issue. Youre thinking of the wrong checkbox. Also I meant to say when its checked on not off thats why there was confusion Im sorry

Philipp Oeser commented

2019-08-22 19:03:01 +02:00

Yes poly_edge_loop_islands_calc or something related seems broken in a way (will check further).

And just as a note: since above is also used in mesh_calc_islands_loop_poly_uv I smell a connection to blender/blender#68954, blender/blender#69035 (pure speculation atm. though...)

Yes `poly_edge_loop_islands_calc` or something related seems broken in a way (will check further). And just as a note: since above is also used in `mesh_calc_islands_loop_poly_uv` I smell a connection to blender/blender#68954, blender/blender#69035 (pure speculation atm. though...)

Bastien Montagne was assigned by Philipp Oeser

2019-08-22 22:10:13 +02:00

Philipp Oeser commented

2019-08-22 22:10:13 +02:00

This is caused by blender/blender@2e91fc39ac
@mont29: mind checking on D5561?

This is caused by blender/blender@2e91fc39ac @mont29: mind checking on [D5561](https://archive.blender.org/developer/D5561)?

blender-admin commented

2019-08-24 08:50:58 +02:00

This issue was referenced by blender/blender@ae0b855a32

This issue was referenced by blender/blender@ae0b855a32ddcffb146d66407785f36e277b631c

Philipp Oeser commented

2019-08-24 08:55:44 +02:00

Changed status from 'Open' to: 'Resolved'

Philipp Oeser closed this issue

2019-08-24 08:55:44 +02:00

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OBJ export: Smoothing group issue #68807